Human rhinoviruses constitute a large genus within the family of Picorna viruses and contain over 90 different serotypes Fox, J. P. , American J. Epid. 103: 345-354 (1976) and Melnick, J. L., Proc. Med. Virol. 26: 214-232 (1980). These RNA viruses affect the respiratory tract of humans and cause acute infections which may lead to colds, coughs, hoarseness, etc., and are generally known as colds Stott, E. J. et al., Ann. Rev. Microbiol., 26: 503-525 (1972). Infections caused by rhinoviruses are among the most common diseases in man. Although the course of the diseases is generally harmless, colds do nevertheless result in general weakening of the organism. This may then give rise to secondary infections caused by other pathogens.
The large group of human rhinoviruses can be subdivided into two sub-groups if the competition for binding sites on the cell surface in human cell culture cells (generally HeLa cells) is used as the criterion for classification. This original classification of a few representatives of the rhinoviruses Lonberg-Holm, K. et al., Nature, 259: 679-681 (1976) has been extended to 88 representatives as a result of a wide range of experiments Cononno, R. J. et al., J. Virol., 57: 7-12 (1986) and Abraham, G. et al. J. Virol., 51: 340-345 (1984). The result of these experiments was to indicate that in spite of the large number, there are surprisingly only two different receptors on the cell surface to which representatives of one or other group of rhinoviruses can bind. Up till now, 78 serotypes of the large "rhinovirus receptor group" and 8 of the small .fwdarw.rhinovirus receptor group" have been classified (RVRG). 2 other representative did not behave clearly so that they could not be definitively classified Abraham, G. et al. J. Virol, 51: 340-345 (1984).
In recent years, a considerable increase in rhinovirus infections has been discovered in densely populated areas. Whereas the majority of other infectious diseases result in a long-lasting or permanent immunity from the pathogen in question, infections caused by rhinoviruses may recur again and again. The reason for the absence of any lasting immunity is the large variety of strains of rhinovirus which show little or no immunological inter-reaction with one another For, J. P. Amer. J. Epidem., 103: 345-354 (1976) and Melnick, J. L., Proc. Med. Virol., 26: 214-232 (1980). After infection has occurred, antibodies against the strain of virus in question can be detected but these do not confer any protection against other rhinovirus strains. In view of the large number of strains circulating in the population, repeated infections by rhinovirus are possible.
Therefore, the presence of only two receptors offers promising possibilities for the successful combating of rhinoviral infections.
Since receptors are generally highly specific, there is a possibility of achieving controlled influence on the receptors by means of suitable substances, for example by blocking the receptors. If substances which block the receptor are used, the penetration of receptor-specific viruses into the cell can be prevented. The same substances which can prevent infection in this way can also be used for the treatment of a manifest rhinovirus infection. The production of such substances is made substantially easier and in some cases made possible for the first time, if the receptor in question is characterised.